JPS63180759A - Multi-disk fluid viscosity type autotensioner - Google Patents

Abstract

PURPOSE:To maintain a stable belt tension with a simple structure, in a belt autotensioner, by absorbing the tensional variation of the belt by the viscous resistance of the multi-disk fluid viscosity type autotensioner via a displacing means. CONSTITUTION:The autotensioner 10 for a timing belt 3 being wound around between a crank-pulley 1 and a cam-pulley 2 has a displacing means which is comprised of a fixed part 12 being fixed to an engine block 8, a sliding sleeve 14 which abuts on the belt 3 so as to be displaced thereto, and a pulley bearing 17. The sliding sleeve 14 provides a prescribed tension to the belt 3 by a coil spring 6 provided between a blaket 20 and a pin 6 projectedly fitted to the cylinder block 8, and further absorbs a part of tensional variation. Further, in the space 30 between the fixed part 12 and the displacing means 14, a multi-disk fluid viscosity damper 25 being comprised of fixed-side plate members 32, displacing-side plate members 28, and viscous fluid is arranged to absorb the tensional variation. Thus, the flapping, tooth skip, or the like of the belt can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an autotensioner that maintains constant tension in a heald. Particularly preferably, automotive O
The present invention relates to a multi-plate fluid viscous auto tensioner used to stably maintain the tension of a camshaft drive timing heald of an HC or DOHC engine, an accessory drive belt, etc.

(Prior Art) The present invention can be widely applied when it is desired to stably maintain the tension of a belt at a constant level. . This initial tension is provided primarily to prevent vibration of the timing heald and tooth skipping between the timing belt and the timing pulley. However, in the case of an engine block made of aluminum or the like and a rubber timing belt containing wires, the coefficient of linear expansion of the former is about four times larger than that of the latter, so the belt tension changes greatly with temperature changes. Put it away. That is, at low temperatures, the shrinkage of the distance between the pulleys is greater than the shrinkage of the belt dimensions, so the belt loosens, leading to increased belt runout and even tooth skipping. Furthermore, at high temperatures, the distance between the pulleys increases more than the belt stretches, so the belt tension increases, causing noise and reducing belt durability.

In order to solve the above-mentioned problems with fixed tensioners, tensioners of the type that have the function of compensating for changes in belt tension have been proposed (for example, Japanese Patent Laid-Open No. 57108343 and Japanese Utility Model No. 59 -49054
).

These conventional tensioners are equipped with an elastic buffer in the radial gap between the rotating part that rotates in contact with the belt and the fixed part attached to the engine block, to prevent increases in belt tension. The structure is configured to compress and deform the buffer body accordingly to reduce the increase in belt tension.

(Problems to be Solved by the Invention) In the conventional tensioner configured as described above, the buffer body is constantly subjected to a belt tension load, so that the buffer body deforms plastically over time. This plastic deformation of the shock absorber lowers the belt tension, making it impossible to maintain the initial tension, which may lead to problems such as increased belt vibration and tooth skipping.

An object of the present invention is to solve these problems and provide an autotensioner that has a simple structure and can maintain stable belt tension at all times.

(Means for Solving the Problems) Referring to FIG. 3, an autotensioner that achieves the object of the present invention includes a fixed part 12 fixed to the engine block 8, which is a base, and a fixed part 12 that is displaceable with respect to the fixed part. a displacing means 14.17 that contacts the heald by pressing the heald; a tensioning means 5 that biases the displacing means to apply a predetermined tension to the heald and absorbs a portion of the tension fluctuation; The vibration absorbing means is a multi-plate type fluid viscous damper containing plate members arranged in a space 30 and stacked one on top of the other and containing a viscous fluid.

(Function) The viscous fluid between the stacked plate members provides viscous resistance when the displacement means is displaced with respect to the fixed part, so that fluctuations in the tension of the belt via the displacement means are absorbed and alleviated.

(Example) An auto tensioner showing a preferred embodiment of the present invention was
An example of application to an engine timing belt will be explained.

FIGS. 1 to 7 show auto tensioners 10 (FIGS. 1 to 4) and 10' (
5 to 7), and FIG. 1 shows a state in which the auto tensioner 10 of the first embodiment is applied to the timing belt 3 of an OHC engine.

First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 1, a timing pulley 1 for a crankshaft and a timing boot U 2 for a camshaft are fixed to the ends of a crankshaft (not shown) and a camshaft extending from an engine block 8 (No. 319), respectively. Belt 3 is wrapped and hung. The timing belt 3 has teeth on its inner circumferential side and meshes with the outer circumferential teeth of each timing boot I71.2, thereby transmitting the rotation of the crankshaft to the camshaft.

The auto tensioner 10 is attached to the engine block 8 so as to apply a predetermined tension (for example, 20 to 30 kgf) to the timing belt 3.

That is, the auto tensioner 10 has a pulley bearing 17.
The outer ring 16 of the timing belt 3 is brought into contact with the outer periphery of the timing belt 3, and is fixed to the engine block 8 via the fixed shaft 12 with a flanged bolt 4.

The pulley bearing 17 includes an outer ring 16, an inner ring 18, and rolling elements 19 interposed between the outer ring 16 and the inner ring 18.
The inner ring 18 is fitted and fixed to the swinging sleeve 14, and the outer ring 16 is rotatable via rolling elements 19.

A swinging sleeve 14 arranged between the inner ring 18 and the fixed shaft 12
Braqueso fixed on! -20 is engine block 8
The auto tensioner 10 as a whole is biased in the direction of the timing belt 3 by a coil spring 5 whose end is hooked to a pin 6 protruding from the engine block 8 at its tip 20a. It is pressed by the belt 3. Therefore, the swinging sleeve 14,
Pulley bearing 17, inner ring 18, rolling element 19, outer ring 1
6) The bracket 20 constitutes a displacement means that is displaced with respect to the fixed shaft 12, which is a fixed part, and comes into contact with the belt.

Further, the coil spring 5 acts as a tension applying means.

Here, an example has been shown in which the outer ring 16 has the part that contacts the timing belt 3 and the part that provides the outer raceway of the rolling elements 19 integrally, but the outer ring and the outer ring of the bearing and the outer belt pulley are separated. It may also be configured as a body.

The fixed shaft 12 includes a circular bottom portion 12a that is in close contact with the engine block 8, and a cylindrical portion 12b that extends from the circular bottom portion 12a to the side opposite to the engine block. The pinned port 4 is inserted into the hollow hole 12e bored in the central axis of the fixed shaft 12, the tip of the port 4 is screwed into the engine block 8, and the fixed shaft 12 is placed stationary in the engine block 8. Fixed.

The swinging sleeve 14 has a first cylindrical portion 14b and a second cylindrical portion 1.
4C, and the first cylindrical portion 14b is connected to the fixed shaft 12.
The second cylindrical portion 14c has the same axis 01 as the fixed shaft 12.
It has an axis 0□ which is eccentric with respect to the other (see Figs. 2 to 4).

The swinging sleeve 14 has a first cylindrical portion 14b that covers the outer periphery of the circular bottom portion 12a of the fixed shaft 12, is loosely fitted to the inner periphery of the second cylindrical portion 14C via a sliding bearing 22, and has a circular shape. An annular cavity 30 is defined between the bottom portion 12a and the bottom portion 12a. A collar of a sliding bearing 22 is interposed between the end of the second cylindrical portion 14c of the swinging sleeve 14 and the collar of the flanged bolt 4 to reduce friction between the swinging sleeve 14 and the collar. . Therefore, the swinging sleeve 14 has the first cylindrical portion 14
The axis of b is 0. It can be rotated around.

A multi-plate fluid viscous vibration absorbing means (damper) 25 is provided within the annular cavity 30 to provide a viscous resistance force against rotation of the swinging sleeve 14 with respect to the fixed shaft 12 .

The multi-plate viscous vibration absorbing damper 25 is constructed by stacking annular plate members and interposing a viscous fluid such as silicone oil in the gap.

The plate members include a fixed side plate member 32 associated with the fixed shaft 12 and a displacement side plate member 28 associated with the swinging sleeve 14.
A plurality of sheets of each sheet are alternately stacked on top of each other, and one sheet of each sheet is shown in FIG. Each plate member 32, 28 is keyed by grooves 32a, 28a that receive the protrusions 12c, 14d of the fixed shaft 12 and the swinging sleeve 14, respectively, and is integrally formed with the fixed shaft 12 and the swinging sleeve 14. It is configured.

The fixed shaft 12 has two protrusions 12c for key coupling protruding radially outward from the outer periphery of the cylindrical portion 12b, and the swinging sleeve 14 has two protrusions 12c protruding radially inward from the inner periphery of the first cylindrical portion 14b. It has two protrusions 14d that protrude in two places. The shape position and number of these protrusions 12C114d are arbitrary, and the plate member 3
2.28 may be fixed or displaced integrally with the fixed shaft 12 and the swinging sleeve 14.

The fixed side plate member 32 has an outer diameter similar to the protrusion 1 of the swinging sleeve 14.
4d and the inner diameter of the cylindrical portion 1 of the fixed shaft 12.
2b. The fixed side plate member 32 is connected to the protrusion 12 of the fixed shaft 12.
It has a groove 32a that fits C.

The displacement side plate member 28 has an outer diameter smaller than the inner circumference of the first cylindrical portion 14b so that it can be fitted into the cavity 30 in the swinging sleeve 14, and an inner diameter larger than the outer side of the protrusion 12C of the fixed shaft 12. have. The displacement side plate member 28 has a groove 28a that fits into the projection 14d of the swinging sleeve 14.

After applying the viscous fluid to the plate members 32.28, they are accommodated in the cavity 30 by matching the alternating stacking projections 14d, 12C with the grooves 28a, 32a. The upper and lower sides of the cavity 30 are sealed by seals 24, 26 which are housed in grooves drilled in the swinging sleeve 14 and the fixed shaft 12. Each plate member 32.2
The gap 8 is maintained at a predetermined value by the thickness of the oil film of the sealed fluid.

The fluid interposed between the plate members 32 and 28 provides viscous resistance when the swinging sleeve 14 rotates relative to the fixed shaft 12 due to vibrations and shocks transmitted to the swinging sleeve 14 via the pulley bearing 17, causing vibrations. and absorb shock.

Next, a second embodiment of the present invention will be described based on FIGS. 5 to 7. Similar elements have been designated with the same reference numeral and a dash.

The auto tensioner 10' of the second embodiment is different from the first embodiment in the configuration of the displacement means for displacing and urging the belt and the configuration of the multi-plate viscous vibration damper.

A swinging sleeve 14' is arranged to cover the fixed shaft 12',
A fixed shaft 12' is fixed onto the engine block 8 by a flanged bolt 4. An inner ring 18' of a pulley bearing 17' is fitted and fixed on the outer periphery of the swinging sleeve 14'.
It is integrally displaced together with the swinging sleeve 14'. An outer ring 16' is rotatably disposed outside the inner ring 18' of the pulley bearing 17' via rolling elements 19'.

A coil spring 5' is wound around the outer periphery of the swinging sleeve 14', and one end of the coil spring 5' is hooked onto the swinging sleeve 14'. The other end of the coil spring 5' is connected to the engine block 8.
It is inserted and held in a hole 8a bored in the hole 8a. The coil spring 5' urges the pulley bearing 17' and the swinging sleeve 14', which are displacement means, in the direction of the belt 3, applies a predetermined tension to the belt 3, and absorbs a part of the tension fluctuation of the belt 3. Acts as a tensioning means.

A long dust 34 is rotatably disposed on the outside of the cylindrical portion of the fixed shaft 12', and a swinging sleeve 14' in which a sliding bearing 22' is fitted on the outside is rotatable.

A space 30' is provided between the fixed shaft 12' and the swinging sleeve 14'.
is provided, and a multi-plate viscous vibration absorbing means (damper) 2 is installed inside.
5' is stored.

The viscous vibration damper 25' includes a movable side plate member 28' of an annular fixed side plate member 32'. Each plate member 28', 3
2' with a predetermined gap, spacers 33 and 36 are used.
, long dust 34, and snap ring 38 are used.

The fixed side plate member 32' is formed into an annular shape having an inner diameter slightly larger than the cylindrical portion of the fixed shaft 12' and an outer diameter slightly smaller than the inner diameter of the spacer 36. On the other hand, the displacement side plate member 28' is
It is formed into an annular shape having an inner diameter slightly larger than the outer diameter of the spacer 33 and an outer diameter slightly smaller than the inner diameter of the space 30'.

The spacer 33 is fitted into the cylindrical portion of the fixed shaft 12' and fits within the inner opening of the displacement side plate member 28', and the spacer 36 is fitted into the inner cavity 30' of the fixed side plate member 32' and the swinging sleeve 14'.
It is a ring member of a size that fits in the space between the inner circumferential surface that forms the ring member.

Since the spacers 33 are arranged alternately in contact with the stationary side plate members 32', the gap between the plate members 32' is set to a predetermined value. The uppermost fixed side plate member 32' is covered with dust 34 for a long time.
Since each plate member 32' is pressed toward the circular bottom of the fixed foot ring 12' by the bolt 4 through the spacer 33, each plate member 32' is fixed to the fixed shaft 12' via the spacer 33. Therefore, the fixed side plate member 32' is held integrally with the fixed shaft 12'.

Since the spacers 36 are arranged alternately in contact with the displacement side plate members 28', the gap between the plate members 28' is set to a predetermined value.

Since the lowermost plate member 28' is pressed and fixed by a snap ring 38, each plate member 28' is fixed to the swing sleeve 14' via the spacer 36. Therefore, the displacement side plate member 28' rotates about the axis 00 together with the swinging sleeve 14'.

Fig. 7 shows an exploded view of the auto tensioner 10'.
There are one plate member 28' and 32', and two spacers 33 and 36.
Shown one by one. The number of plate members 28'32' may be determined as required, and the number of spacers is also determined according to the number of plate members 28'32'.

Plate members 28'32' are coated with a viscous fluid prior to assembly and placed in cavity 30' with spacers 33,36 as described above. The upper and lower parts of the empty chamber 30' are a swinging sleeve 14' and a fixed shaft 1.
Seats 71/24' and 26' are placed in the grooves 2'.

Each plate member 28'32' is maintained at a predetermined spacing by spacers 33,36 and held in place by a fluid film interposed between plate members 28' and 32'.

When the outer ring of the pulley bearing 17' receives tension fluctuations in the belt 3, a portion of the fluctuations are absorbed by the coil spring 5' and a further portion is absorbed by the multi-plate viscous vibration damper lO'.

Although the auto tensioner 10 of the first embodiment does not use the spacer of the second embodiment, the structure is simple, but it is effective to use a spacer to maintain the gap between the plate members more accurately.

Further, in order to maintain the gap between the plate members, fine particles of about several tens of microns may be dispersed in the viscous fluid.

Resin is suitable for the fine particles, and polyamide resin is particularly effective.

Furthermore, it is also advantageous in terms of cost to maintain a gap between the plate members by providing protrusions on the plate members.

(Effects of the Invention) According to the present invention, the tension of the belt can be stably maintained by the multi-plate viscous vibration absorbing means, and problems such as belt flapping and tooth skipping can be eliminated, thereby extending the life of the belt and at the same time suppressing the occurrence of belt noise. be able to.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the auto tensioner according to the first embodiment of the present invention when it is installed in use, Fig. 2 is an enlarged plan view of the first embodiment, and Fig. 3 is 1-I of Fig. 2. 4 is an exploded perspective view of the first embodiment, FIG. 5 is a plan view of the second embodiment of the present invention, and FIG. 6 is a sectional view taken along line nn in FIG. 5. , FIG. 7 is an exploded perspective view of the second embodiment. [Description of main parts] 3- Belt (tension applying means) 12.12' - Fixed shaft (fixed part) 25.25' - Multi-plate fluid viscous damper (vibration absorbing means) Fig. 5 Fig. 6

Claims (1)

[Scope of Claims] 1. A fixed part fixed to the base body, a displacement means that is displaced relative to the fixed part and comes into contact with the belt, and biases the displacement means to apply a predetermined tension to the belt and to apply tension to the belt. a tension imparting means that absorbs a portion of the belt tension fluctuation; and a vibration absorbing means that is disposed between the fixed part and the displacement means and absorbs a part of the belt tension fluctuation; a fixed side plate member that is maintained in a fixed state, a displaceable side plate member that faces the fixed side plate member and is displaced together with the displacing means in relation to the displacing means, and a fluid that provides viscous resistance to displacement of the displaceable side plate member. An auto tensioner characterized by being a multi-plate fluid viscous damper consisting of: 2. Claim 1, characterized in that a plurality of the fixed side plate members and the displacement side plate members are stacked alternately.
Auto tensioner as described in section. 3. The auto according to claim 2, wherein the plurality of fixed side plate members and the plurality of displacement side plate members are each held at a predetermined interval by a spacer member disposed between each plate member. tensioner. 4. The auto tensioner according to claim 1, wherein the fixed portion of the fluid viscous damper is enclosed within a space provided between the displacement means. 5. The auto tensioner according to claim 2, wherein the alternately stacked plate members are held at predetermined intervals by fine particles contained in the fluid. 6. The auto tensioner according to claim 2, wherein the alternately stacked plate members are such that a minimum distance between the plate members is maintained by projections formed on the plate members. 7. The auto tensioner according to claim 1, wherein the fluid is silicone oil.